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Monitoring of cardiac output during exercise in coronary patients: a Doppler study
E Moscarelli1, B Reisenhofer, D Levantest
1C.N.R. Institute of Clinical Physiology, Pisa University, Italy.
Abstract:
The monitoring of aortic blood flow velocities by transcutaneous continuous-wave Doppler was performed in 45 patients to determine, non-invasively, the haemodynamic response to exercise in subsets of coronary patients during a multistage supine exercise tests. Group I consisted of 14 patients with ischaemia on effort (IE); group II, 12 patients with both IE and prior myocardial infarction (MI); group III, 19 patients with MI and no IE; there were also 12 normals. Peak flow velocity (PV) indices of cardiac output (CO), of peripheral resistance (PR) and of stroke work (SW) were measured every min. Resting CO was lower and PR higher in coronary patients than in normals. With exercise, for the same muscular work, CO increased less in IE patients (group I: y = 26.9 + 1.8 x cm sec-1; Group II: y = 21.9 + 1.8 x cm sec-1) than in MI (group III: y = 26.6 + 2.1 x cm s-1) and in normals (y = 35 + 2.7 x cm s-1) and PR decreased less. This suggested a more efficient distribution of CO towards working muscles. A shallower increase in SW was observed in all coronary patients in comparison with normals even if resting SW was significantly lower only in patients with MI (groups II and III). PV increased up to peak exercise only in group III, while it tended to plateau in ischaemic patients even earlier than IE occurred on the ECG.(ABSTRACT TRUNCATED AT 250 WORDS)
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